The present invention relates to a granular fertilizer composition which comprises a coating of a mixture of triethylene glycol and a plant growth regulator on a granular fertilizer and to a process for preparing it.
In order to exhibit efficiently effects of plant growth regulators, it has been known to use the regulators as mixtures with fertilizers. For preparation of the mixtures, there have been known a method of incorporating the regulators into granular fertilizer and another method of coating the granular fertilizer with the regulators.
However, according to the method of incorporation, for example, in the case of complex fertilizer, since plant growth regulator is incorporated into the fertilizer during the preparation of the fertilizer, the plant growth regulator is susceptible to decomposition due to its contact with acids or/and alkalis which are raw materials for the fertilizer. Furthermore, when off-specification products which have been sifted out are to be reused, the plant growth regulator must be removed therefrom and this requires much troubles. Thus, this method is not practical.
On the other hand, the coating method also has problems caused by organic solvents used in preparation.